I could not wait any longer I pulled Gnome 2.24 from Debian experimental and so far, it works like a charm. No big changes are visible at first sight. The launcher icons in my panel now fade towrads me when I click them and every thing feels a bit faster, but that can be my own imagination.

Two things I noticed that are broken:

• My beloved sshmenu applet which is missing the symbol gtk_file_system_error_quark in /usr/lib/ruby/1.8/x86_64-linux/gtk2.so. DBTS mentions that there is a fix upstream and I hope a fixed package will soon be uploaded. Until then I switched to hotssh which does somewhat the same, but runs as a standalone application with SSH-sessions as tabs.
• gnome-keyring-daemon does start when called by libpam-gnome-keyring which leads to a lot of annoying password-prompts when doing SSH, GPG, WebDAV or CIFS through GVFS. There are some warnings in /var/log/auth but I haven't found a fix for it yet:

  gdm[3331]: gnome-keyring-daemon: couldn't lookup keyring component setting: Der Konfigurationsserver konnte nicht kontaktiert werden; mögliche Fehlerquellen sind, dass TCP/IP für ORBit nicht aktiviert ist oder auf Grund eines Systemabsturzes alte NFS-Sperren gesetzt sind. Unter http://www.gnome.org/projects/gconf/ erhalten Sie weitere Informationen (Details -  1: Verbindung zur Sitzung konnte nicht abgerufen werden: dbus-launch failed to autolaunch D-Bus session: No protocol specified
  gdm[3331]: Autolaunch error: X11 initialization failed.